with regard to a wall that is not inclined, the following distinction applies: If the end of the scroll is three handbreadths above the ground, he may roll it back to himself; but if it is below three handbreadths from the ground, it is considered as though the scroll is on the ground, and he must therefore turn it facedown onto the writing.

It was stated in the mishna that Rabbi Yehuda says: Even if the scroll is removed only a needle breadth from the ground, one rolls it back to himself. The Gemara explains: Rabbi Yehuda maintains that in order for an object to be deemed at rest, we require that it rest atop something. Consequently, a scroll that is not actually touching the ground is not considered resting and may be rolled back.

The Gemara asks: But consider that which Rava said with regard to an object located within three handbreadths of the ground. Rava said that according to the opinion of the Rabbis, who disagree with Rabbi Akiva and claim that something in the air is not considered to be at rest, nevertheless, for one to incur liability it is necessary for the object to rest on a surface. Let us say that he stated his halakha in accordance with only one of the tanna’im, but not in accordance with all of them. This is an unacceptable conclusion.

Rather, the Gemara rejects the previous explanation in favor of the following one: The mishna is all in accordance with Rabbi Yehuda, and it is incomplete and is teaching the following: In what case is this statement that once the end of the scroll is within ten handbreadths of the ground it may not be rolled back said? It was said in the case of an inclined wall. But with regard to a wall that is not inclined, even if the end of the scroll is less than three handbreadths from the ground, one may roll it back to himself, as Rabbi Yehuda says: Even if the scroll is removed only a needle breadth from the ground, he rolls it back to himself.

What is the reason for this ruling? The reasoning is that for an object to be considered at rest, we require that it rest atop some surface. Consequently, if the scroll is not actually touching the ground, it is not considered at rest, even if it is less than three handbreadths from the ground.

MISHNA: With regard to a ledge in front of a window, that is ten handbreadths high and four handbreadths wide, one may place objects upon it or remove them from it on Shabbat via the window.

GEMARA: The Gemara clarifies: This ledge, to where does it protrude? If you say that the ledge protrudes into a public domain, one should be prohibited to place an object on it, as we should be concerned lest the object fall and he will forget and come to bring it in from the public domain to a private domain. Rather, it must be that the ledge protrudes into a private domain; but if so, it is obvious that it is permitted to place objects on it and to remove them.

Abaye said: Actually, the mishna is dealing with a case where it protrudes into a public domain, and what is the meaning of that which it teaches: One may place objects upon it? This refers to fragile utensils, which would break instantly if they fell. Consequently, there is no concern that one might then bring them in from the public domain to the private domain.

The Gemara comments: That was also taught in a baraita: With regard to a ledge in front of a window that protrudes into a public domain, one may place on it bowls, cups, small cups [kitoniyot], and saucers. All of these utensils are made of fragile glass or earthenware, which supports Abaye’s opinion.

The baraita continues: And one may use this ledge along the entire length of the wall, if the ledge spans its length, whether in close proximity to the window or removed from it, until the lower ten handbreadths of the wall, but not if the ledge is lower than that. And if there is one other ledge below it but still ten handbreadths above the ground, one may use the lower ledge along the entire length of the wall; but with regard to the upper ledge, one may use it only opposite his window.

The Gemara asks: This upper ledge, what are its circumstances? If it is not four handbreadths deep, although it is an exempt domain with regard to the halakhot of Shabbat, which means it does not pose a problem in itself, one should nonetheless not be permitted to use it even opposite his window, as anything placed on this narrow ledge is likely to fall. Consequently, it is as though he has thrown the object directly to the ground. And if it is four handbreadths deep, let him use the ledge along the entire length of the ledge along the wall.

Abaye said: We are dealing with a case where the lower ledge is four handbreadths deep and the upper ledge is not four handbreadths deep, but the windowsill on the inside completes it to form a surface four handbreadths deep. Accordingly, one may use the part of the upper ledge opposite the window, as it is considered an extension of the window, but the parts to this side or to that side of the window are prohibited, as they are less than four handbreadths deep.

MISHNA: A person may stand in a private domain and move objects that are in a public domain, as there is no concern that he might mistakenly bring them into the private domain. Similarly, one may stand in a public domain and move objects in a private domain, provided that he does not carry them beyond four cubits in the public domain, which is prohibited on Shabbat.

However, a person may not stand in a private domain and urinate into a public domain, nor may one stand in a public domain and urinate into a private domain. And likewise, one may not spit in such a manner that the spittle passes from a private domain to a public domain or vice versa.

Rabbi Yehuda says: Even once a person’s spittle is gathered in his mouth, he may not walk four cubits in the public domain until he spits it out, for he would be carrying the accumulated spittle in his mouth, which is akin to carrying any other object.

GEMARA: Rav Ḥinnana bar Shelamiya would teach this mishna to Ḥiyya bar Rav before Rav as follows: A person may not stand in a private domain and move objects that are in a public domain. Rav said to him: Have you abandoned the majority opinion of the Rabbis and followed the solitary dissenting opinion of Rabbi Meir, who is stringent in this regard?